introduce a centralized place to introduce and inject llvm types into the
clang namespace.  There are a number of LLVM types that are used pervasively
and it doesn't make sense to keep qualifying them.  Start with casting
operators.

llvm-svn: 135574
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index b47a6bdf..c54ced2 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -999,7 +999,7 @@
 
 /// \brief Check whether the given input tree contains any compilation actions.
 static bool ContainsCompileAction(const Action *A) {
-  if (isa<CompileJobAction>(A))
+  if (llvm::isa<CompileJobAction>(A))
     return true;
 
   for (Action::const_iterator it = A->begin(), ie = A->end(); it != ie; ++it)